Organic light emitting diode display

ABSTRACT

An organic light emitting diode display includes a substrate including a display area and a non-display area, subpixels arranged in the display area in a matrix form, a contact electrode that is formed in the non-display area, transfers a power received from the outside, and includes at least one of electrodes included in each subpixel, and a contact unit that includes at least one of insulating layers included in each subpixel and exposes a portion of the contact electrode. An upper electrode included in each subpixel is formed in the display area and the non-display area and is electrically connected to the contact electrode through the contact unit.

This application claims the benefit of Korean Patent Application No.10-2010-0036772 filed on Apr. 21, 2010, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate to an organic light emitting diode(OLED) display.

2. Description of the Related Art

An organic light emitting element used in an organic light emittingdiode (OLED) display has a self-emission structure in which a lightemitting layer is formed between two electrodes on a substrate. The OLEDdisplay may be classified into a top emission type OLED display, abottom emission type OLED display, and a dual emission type OLED displaydepending on an emitting direction of light. The OLED display may beclassified into a passive matrix type OLED display and an active matrixtype OLED display depending on a driving manner.

In the OLED display, each of a plurality of subpixels includes atransistor unit and a light emitting unit. The transistor unit includesa switching transistor, a driving transistor, and a capacitor, and thelight emitting unit includes a lower electrode connected to the drivingtransistor, an organic light emitting layer, and an upper electrode.When a scan signal, a data signal, a power, etc. are supplied to theplurality of subpixels arranged in a matrix form, the selected subpixelsemit light to thereby display an image.

In the OLED display, a contact electrode is formed in a non-display areaso as to supply a power to upper electrodes of the subpixels formed in adisplay area. Further, the contact electrode is electrically connectedto the upper electrode in a formation process of the upper electrode.However, in a related art OLED display, a smooth contact between thecontact electrode formed in the non-display area and the upper electrodeformed in the display area is not achieved, and a short circuit betweenthe contact electrode and the upper electrode is generated. Further, thecontact electrode may be damaged because of a concentration of anelectric filed on an upper edge of the contact electrode.

SUMMARY OF THE INVENTION

In one aspect, there is an organic light emitting diode displaycomprising a substrate including a display area and a non-display area,subpixels arranged in the display area in a matrix form, a contactelectrode that is formed in the non-display area, transfers a powerreceived from the outside, and includes at least one of electrodesincluded in each subpixel, and a contact unit including at least one ofinsulating layers included in each subpixel, the contact unit exposing aportion of the contact electrode, wherein an upper electrode included ineach subpixel is formed in the display area and the non-display area andis electrically connected to the contact electrode through the contactunit.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a block diagram schematically illustrating an organic lightemitting diode (OLED) display;

FIG. 2 illustrates a circuit configuration of a subpixel shown in FIG.1;

FIG. 3 is a plane view schematically illustrating an OLED display shownin FIG. 1;

FIG. 4 is a cross-sectional view of a subpixel shown in FIG. 3;

FIGS. 5 to 7 illustrate the structure of a contact unit and a contactelectrode according to a first exemplary embodiment of the invention;

FIGS. 8 to 10 illustrate the structure of a contact unit and a contactelectrode according to a second exemplary embodiment of the invention;

FIGS. 11 and 12 illustrate the structure of a contact unit and a contactelectrode according to a third exemplary embodiment of the invention;

FIGS. 13 to 15 illustrate the structure of a contact unit and a contactelectrode according to a fourth exemplary embodiment of the invention;

FIGS. 16 and 17 illustrate the structure of a contact unit and a contactelectrode according to a fifth exemplary embodiment of the invention;

FIGS. 18 and 19 illustrate the structure of a contact unit and a contactelectrode according to a sixth exemplary embodiment of the invention;and

FIGS. 20 and 21 illustrate the structure of a contact unit and a contactelectrode according to a seventh exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail embodiments of the inventionexamples of which are illustrated in the accompanying drawings.

FIG. 1 is a block diagram schematically illustrating an organic lightemitting diode (OLED) display. FIG. 2 illustrates a circuitconfiguration of a subpixel shown in FIG. 1. FIG. 3 is a plane viewschematically illustrating the OLED display shown in FIG. 1. FIG. 4 is across-sectional view of a subpixel shown in FIG. 3.

As shown in FIGS. 1 and 2, the OLED display includes a timing controllerTCN, a data driver DDRV, a scan driver SDRV, a power supply unit PWR,and a panel PNL.

The timing controller TCN controls the data driver DDRV using a datadriving signal DDC, and at the same time controls the scan driver SDRVusing a gate driving signal GDC. The timing controller TCN converts avideo signal received from the outside into a data signal DATA andsupplies the data signal DATA to the data driver DDRV. The timingcontroller TCN may be mounted on a printed circuit board (PCB) connectedto the panel PNL in an integrated circuit (IC) form.

The data driver DDRV supplies the data signal DATA to subpixels SPthrough data lines DL1 to DLn positioned on the panel PNL under thecontrol of the timing controller TCN. The data driver DDRV may bemounted on the panel PNL in an IC form.

The scan driver SDRV supplies a scan signal to the subpixels SP throughscan lines SL1 to SLm positioned on the panel PNL under the control ofthe timing controller TCN. The scan driver SDRV may be mounted on thepanel PNL in an IC form or in a gate-in-panel (GIP) form.

The power supply unit PWR produces a high potential power VDD and a lowpotential power GND and supplies them to at least one of the timingcontroller TCN, the data driver DDRV, the scan driver SDRV, and thepanel PNL. The power supply unit PWR may be mounted on the printedcircuit board connected to the panel PNL.

The panel PNL includes the plurality of subpixels SP that are arrangedon a substrate in a matrix form. The subpixels SP may be arranged in apassive matrix form or an active matrix form. As shown in FIG. 2, whenthe subpixels SP are arranged in the active matrix form, each of thesubpixels SP may have a 2T1C structure (i.e., including two transistorsT and one capacitor C) including a switching transistor S, a drivingtransistor T, a capacitor Cst, and an organic light emitting diode D.Alternatively, each subpixel SP may have a structure adding a transistorand a capacitor to the 2T1C structure. In the 2T1C structure, theswitching transistor S, the driving transistor T, and the capacitor Cstmay be defined as a transistor unit, and the organic light emittingdiode D may be defined as a light emitting unit. A connectionrelationship between components constituting the subpixel SP having the2T1C structure is described below with reference to FIG. 2. As shown inFIG. 2, a gate electrode of the switching transistor S is connected tothe scan line SL1 to which the scan signal is supplied, one terminal ofthe switching transistor S is connected to the data line DL1 to whichthe data signal DATA is supplied, and the other terminal of theswitching transistor S is connected to a first node n1. A gate electrodeof the driving transistor T is connected to the first node n1, oneterminal of the driving transistor T is connected to a second node n2connected to a power supply line VDD to which the high potential poweris supplied, and the other terminal of the driving transistor T isconnected to a third node n3. One terminal of the capacitor Cst isconnected to the first node n1, and the other terminal of the capacitorCst is connected to the third node n3. A lower electrode of the organiclight emitting diode D is connected to the third node n3, and an upperelectrode of the organic light emitting diode D is connected to a groundline GND to which the low potential power is supplied.

Although an example where the transistors S and T included in thesubpixel SP are of an n-type is described above, the transistors S and Tmay be of a p-type. The transistors S and T may be an amorphous silicon(a-Si) transistor, a polysilicon transistor, an oxide transistor, anorganic transistor, etc. The transistors S and T may have a bottom gatestructure as well as a top gate structure. The high potential powersupplied through the power supply line VDD may be higher than the lowpotential power supplied through the ground line GND. The high potentialpower and the low potential power are supplied by the power supply unitPWR.

The above-described subpixel SP may operate as follows. As shown in FIG.2, when the scan signal is supplied through the scan line SL1, theswitching transistor S is turned on. Next, when the data signal DATAsupplied through the data line DL1 is supplied to the first node n1 viathe turned-on switching transistor S, the data signal DATA is stored inthe capacitor Cst as a data voltage. Next, when the scan signal is cutoff and the switching transistor S is turned off, the driving transistorT is driven in accordance with the data voltage stored in the capacitorCst. Next, when the high potential power supplied through the powersupply line VDD flows through the ground line GND, the organic lightemitting diode D emits one of red, green, and blue light. The drivingmethod illustrated in FIG. 2 is only one example of the driving methodof the subpixel for a help of an understanding of a circuitconfiguration of the subpixel, and the embodiment of the invention isnot limited to the driving method of the subpixel SP illustrated in FIG.2. Other driving methods of the subpixel may be used for the embodimentof the invention.

As shown in FIGS. 3 and 4, the OLED display includes a pad unit PADformed on a substrate 110 a constituting the panel, a driving IC DIC, adisplay area AA, and a non-display area NA. The substrate 110 aconstituting the panel is encapsulated with a seal substrate 110 b usingan encapsulation material 122, for example, a front sealant, therebyprotecting the subpixels SP formed in the display area AA from theoutside. The pad unit PAD is electrically connected to an externalprinted circuit board and transfers various signals generated by thetiming controller, etc. to the panel. The substrate 110 a constitutingthe panel is defined as the display area AA displaying an image and thenon-display area NA not displaying the image. The subpixels SP arrangedin the matrix form are formed on the substrate 110 a defined as thedisplay area AA, and a contact electrode CE transferring a powerreceived from the outside is formed on the substrate 110 a defined asthe non-display area NA. Although it is not shown, data lines and scanlines connected to the driving IC DIC, a power supply line and a groundline connected to the pad unit PAD, etc. are formed on the substrate 110a defined as the non-display area NA. Although the driving IC DIC shownin FIG. 3 has the structure in which the data driver DDRV and the scandriver SDRV shown in FIG. 1 are formed on one chip, it is not limitedthereto. Further, the contact electrode CE may be selected as the groundline or the power supply line based on the structure of the lowerelectrode and the upper electrode included in the subpixel SP. In theembodiment of the invention, the contact electrode CE is formed on onesurface of the display area AA. However, the contact electrode CE may beformed to surround two, three, or four surfaces of the display area AA.

The structure of the subpixel SP is below described in detail.

As shown in FIG. 4, first and second active layers 111 a and 111 b eachincluding a source region, a channel region, and a drain region areformed on the substrate 110 a. The source region and the drain region ofeach of the first and second active layers 111 a and 111 b may be aredoped with p-type impurities or n-type impurities. A first insulatinglayer 112 is formed on the substrate 110 a to cover the first and secondactive layers I 1 la and 111 b. The first insulating layer 112 may beformed of silicon oxide (SiOx), silicon nitride (SiN_(X)), or othermaterials. First and second gate electrodes 113 a and 113 b are formedon the first insulating layer 112 at locations corresponding to thefirst and second active layers 111 a and 111 b. A second insulatinglayer 114 is formed on the first insulating layer 112 to cover the firstand second gate electrodes 113 a and 113 b and to expose a portion ofthe first active layer 111 a. The second insulating layer 114 may beformed of silicon oxide (SiOx), silicon nitride (SiN_(X)), or othermaterials. Source and drain electrodes 115 a and 115 b connected to theexposed portion of the first active layer 111 a are formed on the secondinsulating layer 114. A capacitor electrode 115 c is formed on thesecond insulating layer 114 in the same manner as the source and drainelectrodes 115 a and 115 b. The capacitor electrode 115 c and the secondgate electrode 113 b form a capacitor. A third insulating layer 116 isformed on the second insulating layer 114 to cover the source and drainelectrodes 115 a and 115 b and the capacitor electrode 115 c. The thirdinsulating layer 116 may be formed of silicon oxide (SiOx), siliconnitride (SiN_(x)), or other materials. A fourth insulating layer 117 isformed on the third insulating layer 116 to expose a portion of thesource and drain electrodes 115 a and 115 b. The fourth insulating layer117 may be formed of silicon oxide (SiOx), silicon nitride (SiN_(X)), orother materials. A lower electrode 118 connected to the exposed portionof the source and drain electrodes 115 a and 115 b is formed on thefourth insulating layer 117. The lower electrode 118 may be selected asan anode electrode or a cathode electrode. When the lower electrode 118is selected as the anode electrode, the anode electrode 118 may beformed of a transparent metal material such as indium-tin-oxide (ITO)and indium-zinc-oxide (IZO), or other materials. A fifth insulatinglayer 119 is formed on the lower electrode 118 to expose a portion ofthe lower electrode 118. The fifth insulating layer 119 may be formed ofan organic material such as benzocyclobutene (BCB)-based resin, acrylicresin, and polyimide resin. Other materials may be used. An organiclight emitting layer 120 is formed on the fifth insulating layer 119 tocover the exposed portion of the lower electrode 118. The organic lightemitting layer 120 may include a hole transport layer, a hole injectionlayer, a light emitting layer, an electron injection layer, and anelectron transport layer. In addition, the organic light emitting layer120 may further include other functional layers. The organic lightemitting layer 120 may emit at least one of red, green, and blue light.At least one of the layers included in the organic light emitting layer120 is formed outside the display area AA as a dummy layer as shown inFIG. 3. An upper electrode 121 is formed on the organic light emittinglayer 120. The upper electrode 121 may be selected as an anode electrodeor a cathode electrode. When the upper electrode 121 is selected as thecathode electrode, the cathode electrode 121 may be formed of an opaquemetal material such as aluminum (Al) and aluminum neodymium (AlNd).Other materials may be used. As shown in FIG. 3, the upper electrode 121is formed in the display area AA and the non-display area NA and iselectrically connected to the contact electrode CE through the contactunit CA. Hence, the upper electrode 121 may receive the high potentialpower or the low potential power through the electrical connectionbetween the upper electrode 121 and the contact electrode CE. In theembodiment of the invention, the contact electrode CE is at least oneelectrode formed in the non-display area NA. The contact unit CA isformed in the non-display area NA and is an insulating layer that allowsa portion of the contact electrode CE to be gently inclined and exposesthe gently inclined portion of the contact electrode CE.

Hereinafter, various embodiments of the structure of the contactelectrode CE and the contact unit CA are described

<First Exemplary Embodiment>

FIGS. 5 to 7 illustrate the structure of a contact unit and a contactelectrode according to a first exemplary embodiment of the invention.

As shown in FIGS. 3 and 5, a contact electrode 113 c (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the first and second gate electrodes113 a and 113 b. Contact units 112, 114 and 119 (CA) include threeinsulating layers. The three insulating layers are formed using the sameprocess and the same material as the first, second, and the fifthinsulating layers 112, 114 and 119. The contact units 112, 114 and 119(CA) cover an edge portion of the contact electrode 113 c (CE) andexpose a middle portion of the contact electrode 113 c (CE).

As shown in FIGS. 3 and 6, the contact electrode 113 c (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the first and second gate electrodes113 a and 113 b. Contact units 112, 114 and 117 (CA) include threeinsulating layers. The three insulating layers are formed using the sameprocess and the same material as the first, second, and the fourthinsulating layers 112, 114 and 117. The contact units 112, 114 and 117(CA) cover an edge portion of the contact electrode 113 c (CE) andexpose a middle portion of the contact electrode 113 c (CE).

As shown in FIGS. 3 and 7, the contact electrode 113 c (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the first and second gate electrodes113 a and 113 b. Contact units 112, 114, 117 and 119 (CA) include fourinsulating layers. The four insulating layers are formed using the sameprocess and the same material as the first, second, fourth, and fifthinsulating layers 112, 114, 117 and 119. The contact units 112, 114, 117and 119 (CA) cover an edge portion of the contact electrode 113 c (CE)and expose a middle portion of the contact electrode 113 c (CE).

Because the upper electrode 121 is electrically connected to the contactelectrode 113 c (CE) through the middle portion of the contact electrode113 c (CE) having a single-layered structure based on theabove-described structure, the upper electrode 121 may smoothly contactthe contact electrode 113 c (CE) and an electric field may be preventedfrom being concentrated on an upper edge of the contact electrode 113 c(CE).

<Second Exemplary Embodiment>

FIGS. 8 to 10 illustrate the structure of a contact unit and a contactelectrode according to a second exemplary embodiment of the invention.

As shown in FIGS. 3 and 8, a contact electrode 115 d (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the source and drain electrodes 115 aand 115 b. Because the contact electrode 115 d (CE) is formed using thesame process and the same material as the source and drain electrodes115 a and 115 b, two insulating layers 112 and 114 are formed under thecontact electrode 115 d (CE). The two insulating layers 112 and 114 arethe first insulating layer 112 and the second insulating layer 114. Acontact unit 119 (CA) includes one insulating layer. The one insulatinglayer is formed using the same process and the same material as thefifth insulating layer 119. The contact unit 119 (CA) covers an edgeportion of the contact electrode 115 d (CE) and exposes a middle portionof the contact electrode 115 d (CE).

As shown in FIGS. 3 and 9, the contact electrode 115 d (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the source and drain electrodes 115 aand 115 b. Because the contact electrode 115 d (CE) is formed using thesame process and the same material as the source and drain electrodes115 a and 115 b, two insulating layers 112 and 114 are formed under thecontact electrode 115 d (CE). The two insulating layers 112 and 114 arethe first insulating layer 112 and the second insulating layer 114. Acontact unit 117 (CA) includes one insulating layer. The one insulatinglayer is formed using the same process and the same material as thefourth insulating layer 117. The contact unit 117 (CA) covers an edgeportion of the contact electrode 115 d (CE) and exposes a middle portionof the contact electrode 115 d (CE).

As shown in FIGS. 3 and 10, the contact electrode 115 d (CE) is formedon the substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the source and drain electrodes 115 aand 115 b. Because the contact electrode 115 d (CE) is formed using thesame process and the same material as the source and drain electrodes115 a and 115 b, two insulating layers 112 and 114 are formed under thecontact electrode 115 d (CE). The two insulating layers 112 and 114 arethe first insulating layer 112 and the second insulating layer 114.Contact units 117 and 119 (CA) include two insulating layers. The twoinsulating layers are formed using the same process and the samematerial as the fourth and fifth insulating layers 117 and 119. Thecontact unit 117 and 119 (CA) cover an edge portion of the contactelectrode 115 d (CE) and expose a middle portion of the contactelectrode 115 d (CE).

Because the upper electrode 121 is electrically connected to the contactelectrode 115 d (CE) through the middle portion of the contact electrode115 d (CE) having a single-layered structure based on theabove-described structure, the upper electrode 121 may smoothly contactthe contact electrode 115 d (CE) and an electric field may be preventedfrom being concentrated on an upper edge of the contact electrode 115 d(CE).

<Third Exemplary Embodiment>

FIGS. 11 and 12 illustrate the structure of a contact unit and a contactelectrode according to a third exemplary embodiment of the invention.

As shown in FIGS. 3 and 11, a contact electrode 118 b (CE) is formed onthe substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the lower electrode 118. Because thecontact electrode 118 b (CE) is formed using the same process and thesame material as the lower electrode 118, two insulating layers 112 and114 are formed under the contact electrode 118 b (CE). The twoinsulating layers 112 and 114 are the first insulating layer 112 and thesecond insulating layer 114. A contact unit 119 (CA) includes oneinsulating layer. The one insulating layer is formed using the sameprocess and the same material as the fifth insulating layer 119. Thecontact unit 119 (CA) covers an edge portion of the contact electrode118 b (CE) and exposes a middle portion of the contact electrode 118 b(CE).

As shown in FIGS. 3 and 12, the contact electrode 118 b (CE) is formedon the substrate 110 a defined as the non-display area NA using the sameprocess and the same material as the lower electrode 118. Because thecontact electrode 118 b (CE) is formed using the same process and thesame material as the lower electrode 118, three insulating layers 112,114 and 117 are formed under the contact electrode 118 b (CE). The threeinsulating layers 112, 114 and 117 are the first insulating layer 112,the second insulating layer 114, and the fourth insulating layer 117. Acontact unit 119 (CA) includes one insulating layer. The one insulatinglayer is formed using the same process and the same material as thefifth insulating layer 119. The contact unit 119 (CA) covers an edgeportion of the contact electrode 118 b (CE) and exposes a middle portionof the contact electrode 118 b (CE).

Because the upper electrode 121 is electrically connected to the contactelectrode 118 b (CE) through the middle portion of the contact electrode118 b (CE) having a single-layered structure based on theabove-described structure, the upper electrode 121 may smoothly contactthe contact electrode 118 b (CE) and an electric field may be preventedfrom being concentrated on an upper edge of the contact electrode 118 b(CE).

<Fourth Exemplary Embodiment>

FIGS. 13 to 15 illustrate the structure of a contact unit and a contactelectrode according to a fourth exemplary embodiment of the invention.

As shown in FIGS. 3 and 13, contact electrodes 113 c and 115 d (CE) areformed on the substrate 110 a defined as the non-display area NA usingthe same process and the same material as the first and second gateelectrodes 113 a and 113 b and the source and drain electrodes 115 a and115 b. Thus, the upper contact electrode 115 d (CE) is formed on thefirst and second insulating layers 112 and 114 exposing a middle portionof the lower contact electrode 113 c (CE). A contact unit 119 (CA)includes one insulating layer. The one insulating layer is formed usingthe same process and the same material as the fifth insulating layer119. The contact unit 119 (CA) covers an edge portion of the uppercontact electrode 115 d and exposes a middle portion of the uppercontact electrode 115 d.

As shown in FIGS. 3 and 14, the contact electrodes 113 c and 115 d (CE)are formed on the substrate 110 a defined as the non-display area NAusing the same process and the same material as the first and secondgate electrodes 113 a and 113 b and the source and drain electrodes 115a and 115 b. Thus, the upper contact electrode 115 d (CE) is formed onthe first and second insulating layers 112 and 114 exposing a middleportion of the lower contact electrode 113 c (CE). Contact units 117 and119 (CA) include two insulating layers. The two insulating layers areformed using the same process and the same material as the fourth andfifth insulating layers 117 and 119. The contact units 117 and 119 (CA)cover an edge portion of the upper contact electrode 115 d and expose amiddle portion of the upper contact electrode 115 d.

As shown in FIGS. 3 and 15, the contact electrodes 113 c and 115 d (CE)are formed on the substrate 110 a defined as the non-display area NAusing the same process and the same material as the first and secondgate electrodes 113 a and 113 b and the source and drain electrodes 115a and 115 b. Thus, the upper contact electrode 115 d (CE) is formed onthe first and second insulating layers 112 and 114 exposing a middleportion of the lower contact electrode 113 c (CE). A contact unit 117(CA) includes one insulating layer. The one insulating layer is formedusing the same process and the same material as the fourth insulatinglayer 117. The contact unit 117 (CA) covers an edge portion of the uppercontact electrode 115 d and exposes a middle portion of the uppercontact electrode 115 d.

Because the upper electrode 121 is electrically connected to the contactelectrodes 113 c and 115 d (CE) through the middle portion of thecontact electrodes 113 c and 115 d (CE) having a two-layered structurebased on the above-described structure, the upper electrode 121 maysmoothly contact the contact electrodes 113 c and 115 d (CE) and anelectric field may be prevented from being concentrated on an upper edgeof the contact electrodes 113 c and 115 d (CE).

<Fifth Exemplary Embodiment>

FIGS. 16 and 17 illustrate the structure of a contact unit and a contactelectrode according to a fifth exemplary embodiment of the invention.

As shown in FIGS. 3 and 16, contact electrodes 113 c and 118 b (CE) areformed on the substrate 110 a defined as the non-display area NA usingthe same process and the same material as the first and second gateelectrodes 113 a and 113 b and the lower electrode 118. Thus, the uppercontact electrode 118 b (CE) is formed on the first and secondinsulating layers 112 and 114 exposing a middle portion of the lowercontact electrode 113 c (CE). A contact unit 119 (CA) includes oneinsulating layer. The one insulating layer is formed using the sameprocess and the same material as the fifth insulating layer 119. Thecontact unit 119 (CA) covers an edge portion of the upper contactelectrode 118 b and exposes a middle portion of the upper contactelectrode 118 b.

As shown in FIGS. 3 and 17, the contact electrodes 113 c and 118 b (CE)are formed on the substrate 110 a defined as the non-display area NAusing the same process and the same material as the first and secondgate electrodes 113 a and 113 b and the lower electrode 118. Thus, theupper contact electrode 118 b (CE) is formed on the first, second, andthe fourth insulating layers 112, 114, and 117 exposing a middle portionof the lower contact electrode 113 c (CE). A contact unit 119 (CA)includes one insulating layer. The one insulating layer is formed usingthe same process and the same material as the fifth insulating layer119. The contact unit 119 (CA) covers an edge portion of the uppercontact electrode 118 b and exposes a middle portion of the uppercontact electrode 118 b.

Because the upper electrode 121 is electrically connected to the contactelectrodes 113 c and 118 b (CE) through the middle portion of thecontact electrodes 113 c and 118 b (CE) having a two-layered structurebased on the above-described structure, the upper electrode 121 maysmoothly contact the contact electrodes 113 c and 118 b (CE) and anelectric field may be prevented from being concentrated on an upper edgeof the contact electrodes 113 c and 118 b (CE).

<Sixth Exemplary Embodiment>

FIGS. 18 and 19 illustrate the structure of a contact unit and a contactelectrode according to a sixth exemplary embodiment of the invention.

As shown in FIGS. 3 and 18, contact electrodes 115 d and 118 b (CE) areformed on the substrate 110 a defined as the non-display area NA usingthe same process and the same material as the source and drainelectrodes 115 a and 115 b and the lower electrode 118. Thus, the uppercontact electrode 118 b (CE) is formed on the first and secondinsulating layers 112 and 114 exposing a middle portion of the lowercontact electrode 115 d (CE). A contact unit 119 (CA) includes oneinsulating layer. The one insulating layer is formed using the sameprocess and the same material as the fifth insulating layer 119. Thecontact unit 119 (CA) covers an edge portion of the upper contactelectrode 118 b and exposes a middle portion of the upper contactelectrode 118 b.

As shown in FIGS. 3 and 19, the contact electrodes 115 d and 118 b (CE)are formed on the substrate 110 a defined as the non-display area NAusing the same process and the same material as the source and drainelectrodes 115 a and 115 b and the lower electrode 118. Thus, the uppercontact electrode 118 b (CE) is formed on the first, second, and fourthinsulating layers 112, 114 and 117 exposing a middle portion of thelower contact electrode 115 d (CE). In the sixth exemplary embodiment,the fourth insulating layer 117 is formed between the upper contactelectrode 118 b and the lower contact electrode 115 d to cover an edgeportion of the lower contact electrode 115 d and to expose the middleportion of the lower contact electrode 115 d. A contact unit 119 (CA)includes one insulating layer. The one insulating layer is formed usingthe same process and the same material as the fifth insulating layer119. The contact unit 119 (CA) covers an edge portion of the uppercontact electrode 118 b and exposes a middle portion of the uppercontact electrode 118 b.

Because the upper electrode 121 is electrically connected to the contactelectrodes 113 c and 118 b (CE) through the middle portion of thecontact electrodes 115 d and 118 b (CE) having a two-layered structurebased on the above-described structure, the upper electrode 121 maysmoothly contact the contact electrodes 115 d and 118 b (CE) and anelectric field may be prevented from being concentrated on an upper edgeof the contact electrodes 115 d and 118 b (CE).

<Seventh Exemplary Embodimen>

FIGS. 20 and 21 illustrate the structure of a contact unit and a contactelectrode according to a seventh exemplary embodiment of the invention.

As shown in FIGS. 3 and 20, contact electrodes 113 c, 115 d and 118 b(CE) are formed on the substrate 110 a defined as the non-display areaNA using the same process and the same material as the first and secondgate electrodes 113 a and 113 b, the source and drain electrodes 115 aand 115 b, and the lower electrode 118. Thus, the middle and uppercontact electrodes 115 d and 118 b (CE) are formed on the first andsecond insulating layers 112 and 114 exposing a middle portion of thelower contact electrode 113 c (CE). A contact unit 119 (CA) includes oneinsulating layer. The one insulating layer is formed using the sameprocess and the same material as the fifth insulating layer 119. Thecontact unit 119 (CA) covers an edge portion of the upper contactelectrode 118 b and exposes a middle portion of the upper contactelectrode 118 b.

As shown in FIGS. 3 and 21, the contact electrodes 113 c, 115 d and 118b (CE) are formed on the substrate 110 a defined as the non-display areaNA using the same process and the same material as the first and secondgate electrodes 113 a and 113 b, the source and drain electrodes 115 aand 115 b, and the lower electrode 118. Thus, the middle and uppercontact electrodes 115 d and 118 b (CE) are formed on the first, second,and fourth insulating layers 112, 114 and 117 exposing a middle portionof the lower contact electrode 113 c (CE). In the seventh exemplaryembodiment, the fourth insulating layer 117 is formed between the uppercontact electrode 118 b and the middle contact electrode 115 d to coveran edge portion of the middle contact electrode 115 d and to expose themiddle portion of the middle contact electrode 115 d. A contact unit 119(CA) includes one insulating layer. The one insulating layer is formedusing the same process and the same material as the fifth insulatinglayer 119. The contact unit 119 (CA) covers an edge portion of the uppercontact electrode 118 b and exposes a middle portion of the uppercontact electrode 118 b.

Because the upper electrode 121 is electrically connected to the contactelectrodes 113 c, 115 d and 118 b (CE) through the middle portion of thecontact electrodes 113 c, 115 d and 118 b (CE) having a three-layeredstructure based on the above-described structure, the upper electrode121 may smoothly contact the contact electrodes 113 c, 115 d and 118 b(CE) and an electric field may be prevented from being concentrated onan upper edge of the contact electrodes 113 c, 115 d and 118 b (CE).

As described above, in the OLED display according to the exemplaryembodiments of the invention, because the contact electrode formed inthe non-display area of the panel smoothly contacts the upper electrodeformed in the display area of the panel, the short circuit between thecontact electrode and the upper electrode can be prevented and thedamage of the contact electrode resulting form the concentration of theelectric field on the upper edge of the contact electrode can beprevented. Further, the exemplary embodiments of the invention canprovide the structure of the contact electrode capable of reducing theline resistance.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. An organic light emitting diode display comprising: a substrateincluding a display area and a non-display area; subpixels arranged inthe display area in a matrix form; a contact electrode that is formed inthe non-display area, transfers a power received from the outside, andincludes at least one of electrodes included in each subpixel; and acontact unit including at least one of insulating layers included ineach subpixel, the contact unit exposing a portion of the contactelectrode, wherein an upper electrode included in each subpixel isformed in the display area and the non-display area and is electricallyconnected to the contact electrode through the contact unit, wherein thecontact electrode is formed as a gate electrode included in eachsubpixel, wherein the insulating layer formed in the contact unitincludes at least three of the insulating layers included in eachsubpixel.
 2. The organic light emitting diode display of claim 1,wherein the contact electrode is formed using the same process and thesame material as at least one of the electrodes included in eachsubpixel, wherein the insulating layer formed in the contact unit isformed using the same process and the same material as at least one ofthe insulating layers included in each subpixel.
 3. The organic lightemitting diode display of claim 1, wherein at least two insulatinglayers are formed under the contact electrode, and the contact electrodeis formed as a source electrode and a drain electrode included in eachsubpixel, wherein the insulating layer formed in the contact unitincludes at least one of the insulating layers included in eachsubpixel.
 4. The organic light emitting diode display of claim 1,wherein the contact electrode is formed as a gate electrode, a sourceelectrode, and a drain electrode included in each subpixel, wherein theinsulating layer formed in the contact unit includes at least one of theinsulating layers included in each subpixel.
 5. The organic lightemitting diode display of claim 1, wherein the contact electrode isformed as a gate electrode, a source electrode, a drain electrode, and alower electrode included in each subpixel.
 6. An organic light emittingdiode display comprising: a substrate including a display area and anon-display area; subpixels arranged in the display area in a matrixform; a contact electrode that is formed in the non-display area,transfers a power received from the outside, and includes at least oneof electrodes included in each subpixel; and a contact unit including atleast one of insulating layers included in each subpixel, the contactunit exposing a portion of the contact electrode, wherein an upperelectrode included in each subpixel is formed in the display area andthe non-display area and is electrically connected to the contactelectrode through the contact unit, wherein at least three insulatinglayers are formed under the contact electrode, and the contact electrodeis formed as a lower electrode included in each subpixel, wherein theinsulating layer formed in the contact unit includes at least one of theinsulating layers included in each subpixel.
 7. An organic lightemitting diode display comprising: a substrate including a display areaand a non-display area; subpixels arranged in the display area in amatrix form; a contact electrode that is formed in the non-display area,transfers a power received from the outside, and includes at least oneof electrodes included in each subpixel; and a contact unit including atleast one of insulating layers included in each subpixel, the contactunit exposing a portion of the contact electrode, wherein an upperelectrode included in each subpixel is formed in the display area andthe non-display area and is electrically connected to the contactelectrode through the contact unit, wherein the contact electrode isformed as a gate electrode and a lower electrode included in eachsubpixel, wherein the insulating layer formed in the contact unitincludes at least three of the insulating layers included in eachsubpixel.
 8. An organic light emitting diode display comprising: asubstrate including a display area and a non-display area; subpixelsarranged in the display area in a matrix form; a contact electrode thatis formed in the non-display area, transfers a power received from theoutside, and includes at least one of electrodes included in eachsubpixel; and a contact unit including at least one of insulating layersincluded in each subpixel, the contact unit exposing a portion of thecontact electrode, wherein an upper electrode included in each subpixelis formed in the display area and the non-display area and iselectrically connected to the contact electrode through the contactunit, wherein the contact electrode is formed as a source electrode, adrain electrode, and a lower electrode included in each subpixel,wherein the insulating layer formed in the contact unit includes atleast three of the insulating layers included in each subpixel.